Estimated Reading Time: 4 minutes

Picture the scene…

You are working in minors where you are about to see a patient with “a rash”…

Learning Objective

To learn about the diagnosis and treatment of Lyme disease.

RCEM Curriculum

CAP28 – Rash

Read the NICE guidance about the diagnosis of Lyme Disease

Then review these two guidance charts about treatment (click to open in a new window).

Listen to Lauren Westafer and Jeremy Faust on FOAMCast discussing the diagnosis and treatment of Lyme dsease. Although they are based in the US, and mention some geographical loactions particular to them, Lyme is still prevalent in the UK (especially in the South of England and Scottish Highlands) and treatment regimes are similar. As you listen augment any notes you made after reading the NICE guideline.

This part of the teaching session should be lead by an experienced clinican. The cases provided are merely examples and if possible the learners should be encouraged to discuss patients they have seen in their clinical practice.

A 35 year old who has been out walking the New Forest presents thinking they have been bitten by a tick, but have no rash.

1, What features are important in the history?

Post exposure prophylaxis may be indicated if meeting all of the following:

1. An engorged Ixodes scapularis tick is removed after at least an estimated 36 hours of attachment.

2. Prophylaxis is started within 72 hours of tick removal.

3. Borrelia burgdorferi prevalence in local ticks is known to be greater than 20%.

2, What would you use for prophylaxis?

Primary option for prophylaxis is doxycycline: children: 4 mg/kg/day orally as a single dose; adults: 200 mg orally as a single dose

Contraindications include children <8 years of age (in some countries) and pregnancy, or lactation.

In the UK, doxycycline is not recommended for use in children <12 years of age. In the US, the American Academy of Pediatrics endorses short-term use (<21 days) of doxycycline for Lyme disease in children <8 years old.

Patients who cannot take doxycycline are started on treatment if early symptoms develop.

A 28 year old woman presents with the rash below

This is erythema migrans (named from the latin meaning “migrating redness”). It is caused by a skin reaction to the infecting agent itself. It may feel warm, but it rarely itchy.

They may have a ‘flu like’ illness:

  • Fever,
  • Headache
  • Myalgias
  • Fatigue
  • Arthralgias

Nausea and vomiting are rare.

Oral antibiotics are recommended for patients with Lyme disease (local or disseminated) with erythema migrans, in the absence of cardiovascular or neurological manifestations.

Oral doxycycline is the treatment of choice, with amoxicillin and azithromycin as other options.

Macrolides (e.g., azithromycin or erythromycin) are not recommended as first-line treatment. They should be reserved for patients with intolerance or allergy to first-line agents, with close monitoring for resolution of symptoms.

First-generation cephalosporins are ineffective for the treatment of Lyme disease.

Various studies have used 10 to 21 days of treatment. Although there is no clear consensus, 14 days is adequate in most cases. A recent study conducted in Slovenia showed similar efficacy between 10-day and 15-day courses of doxycycline in patients with typical solitary erythema migrans. Azithromycin is given for only 7 to 10 days.

A 7 year old boy presents with the rash below. He feels unwell and has intermittant fevers.

Doxycycline is contraindicated in children <8 years of age in some countries, and during pregnancy and lactation; in the UK, doxycycline is not recommended for use in children <12 years of age.

In the US, the American Academy of Pediatrics endorses short-term use (<21 days) of doxycycline for Lyme disease in children <8 years old. Amoxicillin and cefuroxime may be used safely in these patients.

In this session we have learned about the clinical assessment of the patient with tick bites and rash, and the diagnosis and treatment of Lyme Disease.


  • Not all tick bites need prophylaxis
  • The treatment of choice for Lyme Disease with erythema migrans is doxycycline (although this is not recommended in the UK for children under 8 years old or children under 12 who wweight less than 33kg).
  • If the patient has erythema migrans there is no need to perform any other testing.
  • Timing of testing is vital – follow this flowchart if in doubt –

In order to embed today’s learning further, reflect on what you have learnt and record in your portfolio whether it has had any impact (or is expected to have any impact) on your performance and practice.

Was this a topic that you were confident you knew already? Which parts were new to you? Were there elements that you will use on your next clinical shift.

Dscuss this session with your colleagues – were there people who missed it who you can share the highlights with?

References and Further Reading

1, Lyme Disease [NG95]. Nice Guideline. Published date: 11 April 2018 Last updated: 17 October 2018. Accessed 11th September 2020

2, Lyme Disease. BMJ Best Practice.